(1) Field of the Invention
The present invention relates to an overhead projector, and more particularly to a projector capable of correctly positioning a file page with ease after it has been rotated through 90.degree. or 180.degree. or turned upside down for changing over the projection methods of the projector, such as reflection and transmission projections.
(2) Description of the Prior Art
In projecting picture images of slide films, there are the reflection projection wherein images are projected onto a white or silver screen, and the transmission projection wherein images are projected onto a screen which transmits and diffuses light beams, and recently the latter has been widely used. With the transmission projection, a user is on the back side or rear side of the screen, so that the screen is accessible for detailed observation without casting a shadow of the user onto the screen and the picture image on the screen can be directly copied onto a blank paper. In addition to such advantages, the picture images can be clearly observed in a bright room and is given a cubic or three-dimensional mode.
Heretofore, however, when a projector is changed from the reflection projection to the transmission projection if desired, turned over images will be projected on the screen. Consequently, a mirror should be arranged between the projector and the screen, or the slide films received in a magazine should be turned upside down to obtain errect images on the screen.
However, the arrangement of the mirror requires equipment in connection therewith. In the event of turning the slide film upside down, a number of slide films in magazines or file pages must be turned upside down one by one which is very troublesome.